This invention relates to adhesion proteins (as defined below), and in particular to lymphocyte function associated antigen-3 (LFA-3), a glycoprotein which is widely distributed on the surfaces of almost all human cells, including monocytes, granulocytes, cytolytic T lymphocytes, B lymphoblastoid cells, platelets, and fibroblasts.
LFA-3 is a ligand for cluster of differentiation 2 (CD2), another glycoprotein, found on the surfaces of T lymphocytes. These two glycoproteins interact to mediate T lymphocyte adhesion to target cells. Similarly, binding of thymocyte to thymic epithelial cells requires CD2 on the thymocyte and LFA-3 on the thymic epithelial cell. LFA 3 in purified form inhibits intercellular adhesion between T lymphocytes and erythrocytes and mediates aggregation of T lymphocytes.